1. Field of the Invention
The present invention relates to expandable materials; and, more particularly, to sheet materials that are capable of expansion for use in packaging, fencing and other structures.
2. Description of the Prior Art
U.S. Pat. No. 6,929,843 or the Fence Tape Patent discloses and claims a tape barrier consisting of flexible material having generally parallel edges and substantially greater length than width. Cuts are made into the tape at intervals along the tape, forming slits that define cross members that extend generally along the length of the tape. The slits may be completed cuts so that the cross members are free to fall away from the tape on perforations that enable the cross members to be separated from the tape by tearing along the perforations. When the tape is deployed generally horizontally, the cross members fall vertically to provide cross members along the length of the resulting tape structure.
The contemplated use of the product taught in the Fence Tape Patent is a flexible plastic barrier tape segment cut from a continuous roll of tape. The ends of the segment are affixed to two mounting elements (e.g., vertical posts). A user then grasps the bottom of the tape segment, and pulls in a horizontal direction. As a result, the tape segment expands vertically to form a lattice or fence type structure with horizontal and vertical elements that create square voids. It is important to note that the tape expands in only one direction (i.e., vertical), while the other direction (i.e., horizontal) retains a constant length. The tape expands in width only, and does not expand in the longitudinal direction.
Australian Patent Application Serial No. 199226388 A1, filed by Gregory Beaumont on Oct. 14, 1992, teaches a safety net produced from a sheet of plastic material that has been slit to produce a formation of two repeating polygon shaped openings when expanded by tensioning opposite edges. The Beaumont application contemplates use of the invention as a fence barrier.
Sheet material that produces a lattice structure when pulled from opposite sides has been around for a while. Another example of such a product is taught in U.S. Pat. No. 2,656,291 issued to Doll, et. al. on Oct. 20, 1993. Doll discloses a slit sheet that when pulled, deploys to a lattice with rhombus shaped voids. Yet another example may be found in U.S. Pat. Nos. 5,667,871 and 5,688,578, both issued to Goodrich, et. al. on Sep. 16, 1997 and Nov. 18, 1997, respectively. Goodrich discloses a slit sheet of heavy paper that when pulled in opposite directions, expands into a lattice with hexagonal voids. A companion patent to Goodrich is U.S. Pat. No. 5,538,778 issued to Hurwitz, et. al. on Jul. 23, 1996. Doll, Hurwitz, and Goodrich contemplated use of their inventions as a packing material.
The Fence Tape Patent taught a continuous roll of material cut with specially shaped slits along the entire length of the material in the longitudinal direction, and which expands into a lattice structure when pulled in a single direction. In these prior art patents, the material expands in one direction while becoming narrower in the other direction.
The Fence Tape Patent does not limit its disclosure to traditional plastic barrier tape. The patent contemplates other uses for a continuous roll of slit material that deploys into a lattice. For example, if heavy paper is used, the material may deploy directly from the continuous roll into a packing material. Expansion of the material produces a lattice structure with square or rhombus shaped voids bounded by longitudinal members and cross members. The lattice structure produced has a unique advantage. The longitudinal members reside mainly in the plane of the paper, but the cross members twist into a non-coplanar direction. Therefore, if the material is rolled around an object, the rolled surfaces will be separated by a distance equal to the non-planar dimension of the cross members.
When used for packing, much more material is required than for fence barriers, and the lattice dimensions need to be smaller. There are many more voids per unit area in the packing material than in the fence barrier. The problem with the continuous material produced with the Fence Tape Patent for use as packing material is the difficulty of deploying (i.e., expanding) a sufficient quantity of material as it comes off the roll. As the roll unravels, a user must pull on many sections in order to fully deploy the material. A single pull on the material expands it about six inches in width. Thus, a user needs to pull on the material repeatedly until it expands as desired. The subject expandable web material having curvilinear structure solves this problem by teaching a dispenser that expands the material to its full width as it unravels from the roll.